Design for cold plate assembly for server liquid cooling of electronic racks of a data center

ABSTRACT

A cooling module assembly includes a cold plate to be positioned adjacent to an exterior surface of a processor to receive heat radiated from the processor, and a cold plate mounting bracket attached to the cold plate to mount the cold plate onto the processor. The cold plate mounting bracket includes a first set of mounting slots to be aligned with a second set of mounting slots disposed on a processor mounting bracket that mounts the processor. Each of the mounting slots in the first set and the second set is configured in an asymmetric shape. The first and second sets of mounting slots allow a mounting pin to be inserted through in a first angle and to rotate from the first angle to a second angle after the insertion to interlock the cold plate with the exterior surface of the processor with proper mounting pressure loaded.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to data centers.More particularly, embodiments of the invention relate to a cold platedesign for servers of a liquid cooling system for electronic racks indata centers.

BACKGROUND

Heat removal is a prominent factor in a computer system and data centerdesign. The number of high performance electronics components such ashigh performance processors packaged inside servers has steadilyincreased, thereby increasing the amount of heat generated anddissipated during the ordinary operations of the servers. Thereliability of servers used within a data center decreases if theenvironment in which they operate is permitted to increase intemperature over time. Maintaining a proper thermal environment iscritical for normal operations of these servers in data centers, as wellas the server performance and lifetime. It requires more effective andefficient heat removal solutions especially in the cases of coolingthese high performance servers.

Power intensive processors enable the solution of intensive computingsuch as deep learning. Electrical servers having those processors, i.e.,high-power central processing units (CPUs) and/or general-purpose orgraphical processing units (GPUs), have a very high power density pervolumetric space, and hence, traditional simple air cooling is verychallenging. Direct-to-chip liquid cooling provides a better coolingperformance for those power-intensive processors, and saves energyconsumption compared to an air-cooling only approach.

Typically, liquid cooling is provided to a processor using a cold plateattached onto an external surface of the processor. Cooling liquid isdistributed through the cold plate to exchange heat generated from theprocessor. Similar to a heat sink, thermal interface material may beused to fill the gaps in the surfaces of the device and the cold plate.The cold plate should be fully in contact with the processor to enablethe cold plate to function properly. Without proper contact, the coldplate may not be able to as it is designed or it may fail. This requiresa proper mounting pressure. However, if the cold plate mounting pressureis too much, it may cause potential damage to the processor. There hasbeen a lack of efficient ways to mount a cold plate onto a processorwith proper pressure without causing damage to the processor.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example and notlimitation in the figures of the accompanying drawings in which likereferences indicate similar elements.

FIG. 1 is a block diagram illustrating an example of a data centerfacility according to one embodiment.

FIG. 2 is a block diagram illustrating an example of an electronic rackaccording to one embodiment.

FIG. 3 is a block diagram illustrating an example of an electronic rackaccording to another embodiment.

FIG. 4 shows an exploded perspective view of a cold plate configurationaccording to one embodiment.

FIGS. 5A and 5B show top and bottom perspective view of a cold plateconfiguration according to certain embodiments.

FIG. 6 shows a bottom view of a cold plate configuration according toone embodiment.

FIGS. 7A and 7B show an example of a mounting pin according to oneembodiment.

FIG. 8 shows an example of a server blade and cooling module withmultiple cold units assembled according to one embodiment.

DETAILED DESCRIPTION

Various embodiments and aspects of the inventions will be described withreference to details discussed below, and the accompanying drawings willillustrate the various embodiments. The following description anddrawings are illustrative of the invention and are not to be construedas limiting the invention. Numerous specific details are described toprovide a thorough understanding of various embodiments of the presentinvention. However, in certain instances, well-known or conventionaldetails are not described in order to provide a concise discussion ofembodiments of the present inventions.

Reference in the specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin conjunction with the embodiment can be included in at least oneembodiment of the invention. The appearances of the phrase “in oneembodiment” in various places in the specification do not necessarilyall refer to the same embodiment.

According to some embodiments, an innovative mechanical design for acold plate is used in liquid cooling. The design provides means toquickly, efficiently, and safely assemble and disassemble the coldplates to the chips without requiring any tool. This mechanism alsoprovides a novel design to ensure a proper mounting pressure can beloaded to the cold plate and to the chip/processor. The goal is toensure that the cold plate base surface is fully in contact with theprocessor (eliminating the thermal resistance and at the same timemeeting the mounting pressure requirements). When to disassemble thecold plates from the motherboards, devices or chips, (for example,replacing the cold plate or the GPU card), this design enablesdisassembling the cold plate quickly without requiring any tool.

In one embodiment, mounting pins and mounting brackets are utilized tomount a cold plate on a particular location of a printed circuit board(PCB) or motherboard. The function of mounting brackets and mountingpins are to mount a cold plate onto the motherboard easily. This enablesthe cold plate to be mounted on all horizontal directions. Pressure isloaded by an operator to the cold plate to enable a fully contact with asurface of a processor. It only requires the operator to push the coldplate from the top. The required mounting pressure is provided by themounting pins and the associated springs. The main pressure is providedby at least two or four mounting pins and the associated springs. Oncethe mounting pressure is loaded to the cold plate and the processor, thespring provides and maintains a proper pressure. The cold plate can beeasily disassembled by releasing the mounting pins, for example, byrotating the mounting pins from a locked position to an unlockedposition.

According to one aspect of the invention, a cooling module assembly(also referred to as a cold plate assembly) for cooling a processor of adata processing system includes a cold plate (e.g., a heat sink with awater fin) to be positioned adjacent to an exterior surface of aprocessor to receive heat radiated from the processor. A liquiddistribution channel formed within the cold plate to distribute acooling liquid through the cold plate to exchange the heat carried bythe cold plate. The liquid distribution channel includes an ingress port(also referred to as an inlet) to be coupled a liquid supply line toreceive the cooling liquid from an external liquid source and an egressport (also referred to as an outlet) to be coupled to a liquid returnline to return the cooling liquid having the exchanged heat back to theexternal liquid source.

In one embodiment, the cooling module assembly further includes a coldplate mounting bracket attached to the cold plate to mount the coldplate onto the external surface of the processor. The cold platemounting bracket includes a first set of mounting slots to be alignedwith a second set of mounting slots disposed on a processor mountingbracket that mounts a processor onto a motherboard of the dataprocessing system. Each of the mounting slots in the first set and thesecond set is configured in an asymmetric shape. The first set ofmounting slots and the second set of mounting slots allow one or moremounting pins to be inserted therethrough in a first angle and to rotatefrom the first angle to a second angle after the insertion to interlockthe cold plate with the exterior surface of the processor.

In one embodiment, each mounting pin is configured to insert through acenter of a spring in order to insert through a corresponding mountingslot of the first set. The spring is compressed when the mounting pin isin a locked position to provide a force to push the cold plate againstthe exterior surface of the processor. A force coefficient of the springis selected such that the force applied to the processor is optimal toallow transferring the heat to the cold plate without applying too muchpressure to potentially damage the processor, at the same time,providing sufficient tightening force. The force coefficient of thespring is configured based on a design specification of the processor,such that the force applied to the processor due to a compression of thespring when the mounting pin is in the locked position is less than amaximum force can be applied to the processor specified by the designspecification.

In one embodiment, each mounting pin includes a head portion, a tipportion, and a shank portion coupling the head portion to the tipportion. A cross section of the tip portion is configured to have across section shape conforming to the asymmetric shape of the mountingslots of the first set and the second set. A longitudinal dimension of across section of the tip portion is larger than a lateral dimension ofeach mounting slot. A lateral dimension of the cross section of the tipportion is smaller than the lateral dimension of the mounting slot. Eachmounting pin is inserted through a corresponding mounting slot of thefirst set and the second set in a first angle, such that thelongitudinal axis of the cross section of the tip portion of themounting pin is aligned with a longitudinal axis of the correspondingmounting slots (which position is referred to as an unlocked position).When each mounting pin is rotated from the first angle to the secondangle, the longitudinal axis of the cross section of the tip portion ofthe mounting pin is not aligned with the longitudinal axis of thecorresponding mounting slots (which position is referred to as a lockedposition).

In one embodiment, each mounting pin in a locked position allows the tipportion and the head portion of the mounting pin to lock a cold platemounting bracket of a corresponding cold plate and a processor mountingbracket of a corresponding processor together. At least the shankportion of each mounting pin is inserted through the spring. The springis compressed between the head portion and the cold plate mountingbracket when the mounting pin is inserted through the mounting slots ofthe first set and second set. When the mounting pin is in the lockedposition, the tip portion of the mounting pin prevents the mounting pinfrom being retracted or removed from the mounting slot of the processormounting bracket. Meanwhile, the spring (compressed between the head ofthe mounting pin and the cold plate mounting bracket) pulls the tipportion against the processor mounting bracket to interlock with eachother. In one embodiment, the asymmetric shape of each mounting slot isan ellipse shape or a rectangular shape.

According to another aspect of the invention, an electronic rack used ina data center includes a rack liquid supply line, a rack liquid returnline, and a stack of server blades coupled to the rack cooling liquidsupply line and the rack cooling liquid return line. Each server bladecontains one or more data processing systems. Each server blade includesone or more processors or other devices each attached to a coolingmodule assembly. Each cooling module assembly can be implemented as acooling module assembly described above.

According to another aspect of the invention, a data center includes aroom liquid supply line coupled to a cooling liquid source, a roomliquid return line coupled to the cooling liquid source, and an array ofelectronic racks. Each of the electronic racks includes a rack liquidsupply line coupled to the room liquid supply line, a rack liquid returnline coupled to the room liquid return line, and a stack of serverblades coupled to the rack cooling liquid supply line and the rackcooling liquid return line. Each server blade includes one or more dataprocessing systems. Each server blade includes one or more processors orother devices each attached to a cooling module assembly. Each coolingmodule assembly can be implemented as a cooling module assemblydescribed above.

FIG. 1 is a block diagram illustrating an example of a data center ordata center unit according to one embodiment. In this example, FIG. 1shows a top view of at least a portion of a data center. Referring toFIG. 1, according to one embodiment, data center system 100 includesrows of electronic racks of information technology (IT) components,equipment or instruments 101-102, such as, for example, computer serversor computing nodes that provide data services to a variety of clientsover a network (e.g., the Internet). In this embodiment, each rowincludes an array of electronic racks such as electronic racks110A-110N. However, more or fewer rows of electronic racks may beimplemented. Typically, rows 101-102 are aligned in parallel withfrontends facing towards each other and backends facing away from eachother, forming aisle 103 in between to allow an administrative personwalking therein. However, other configurations or arrangements may alsobe applied.

In one embodiment, each of the electronic racks (e.g., electronic racks110A-110N) includes a housing to house a number of electronic racks ofIT components operating therein. The electronic racks can include a heatremoval liquid manifold, a number of server slots, and a number ofserver blades capable of being inserted into and removed from the serverblades or server slots. Each server blade represents a computing nodehaving one or more processors, a memory, and/or a persistent storagedevice (e.g., hard disk). At least one of the processors is attached toa liquid cold plate (also referred to as a cold plate assembly) toreceive cooling liquid. In addition, one or more optional cooling fansare associated with the server blades to provide air cooling to thecomputing nodes contained therein. Note that the heat removal system 120may be coupled to multiple data center systems such as data centersystem 400.

In one embodiment, heat removal system 120 includes an external liquidloop connected to a cooling tower or a dry cooler external to thebuilding/housing container. The heat removal system 120 can include, butis not limited to evaporative cooling, free air, rejection to largethermal mass, and waste heat recovery designs. Heat removal system 120may include or be coupled to a cooling liquid source that providecooling liquid.

In one embodiment, each server blade is coupled to the heat removalliquid manifold modularly such that a server blade can be removed fromthe electronic rack without affecting the operations of remaining serverblades on the electronic rack and the heat removal liquid manifold. Inanother embodiment, each server blade is coupled to the heat removalliquid manifold (also referred to as a cooling liquid manifold) througha quick-release coupling assembly having a first liquid intake connectorand a first liquid outlet connector coupled to a flexible hose todistribute the heat removal liquid to the processors. The first liquidintake connector is to receive heat removal liquid via a second liquidintake connector from a heat removal liquid manifold mounted on abackend of the electronic rack. The first liquid outlet liquid connectoris to emit warmer or hotter liquid carrying the heat exchanged from theprocessors to the heat removal liquid manifold via a second liquidoutlet connector and then back to a coolant distribution unit (CDU)within the electronic rack.

In one embodiment, the heat removal liquid manifold disposed on thebackend of each electronic rack is coupled to liquid supply line 132 toreceive heat removal liquid (also referred to as cooling liquid) fromheat removal system 120. The heat removal liquid is distributed througha liquid distribution loop attached to a cold plate assembly on which aprocessor is mounted to remove heat from the processors. A cold plate isconfigured similar to a heat sink with a liquid distribution tubeattached or embedded therein. The resulting warmer or hotter liquidcarrying the heat exchanged from the processors is transmitted vialiquid return line 131 back to heat removal system 120. Liquidsupply/return lines 131-132 are referred to as data center or roomliquid supply/return lines (e.g., global liquid supply/return lines),which supply heat removal liquid to all of the electronic racks of rows101-102. The liquid supply line 132 and liquid return line 131 arecoupled to a heat exchanger of a CDU located within each of theelectronic racks, forming a primary loop. The secondary loop of the heatexchanger is coupled to each of the server blades in the electronic rackto deliver the cooling liquid to the cold plates of the processors.

In one embodiment, data center system 100 further includes an optionalairflow delivery system 135 to generate an airflow to cause the airflowto travel through the air space of the server blades of the electronicracks to exchange heat generated by the computing nodes due tooperations of the computing nodes (e.g., servers) and to exhaust theairflow exchanged heat to an external environment 108 outside ofhousing/room/building. For example, air supply system 135 generates anairflow of cool/cold air to circulate from aisle 103 through electronicracks 110A-110N to carry away exchanged heat. The cool airflows enterthe electronic racks through their frontends and the warm/hot airflowsexit the electronic racks from their backends. The warm/hot air withexchanged heat is exhausted from room/building. Thus, the cooling systemis a hybrid liquid-air cooling system, where a portion of the heatgenerated by a processor is removed by cooling liquid via thecorresponding cold plate, while the remaining portion of the heatgenerated by the processor is removed by airflow cooling.

According to one embodiment, each of the electronic racks includes anoptional rack management unit (RMU) coupled to the CDU and each of thecomputing nodes of the electronic rack (not shown). The RMC periodicallyor constantly monitors operating status of the CDU, computing nodes, andcooling fans. The operating data of the operating status may include theoperating temperatures of each processor, cooling liquid, and anairflow, etc. measured at real time. Based on the operating datareceived from various components, the RMU performs an optimization usingan optimization function to determine the optimal pump speed of a liquidpump of the CDU and optimal fan speeds of the cooling fans, such thatthe power consumption of the liquid pump and the cooling fans reachesminimum, while the liquid pump and the cooling fans are operatingproperly according to their respective specifications (e.g., the speedsof the liquid pump and cooling fans are within their respectivepredefined ranges).

That is, the optimization is performed at a global level by optimizingall components involved simultaneously, such that 1) the temperatures ofthe processors are below their respective reference temperatures, 2) thetotal power consumption by the liquid pump and the cooling fans reachesminimum, and 3) each of the liquid pump and cooling fans operates withintheir respective specification. The optimal pump speed and the optimalfan speeds are then utilized to configure the liquid pump and thecooling fans. As a result, the total power consumption by the liquidpump and the cooling fans reaches minimum while the processors of thecomputing nodes operate properly.

FIG. 2 is block diagram illustrating an electronic rack according to oneembodiment. Electronic rack 200 may represent any of the electronicracks as shown in FIG. 1, such as, for example, electronic racks110A-110N. Referring to FIG. 2, according to one embodiment, electronicrack 200 includes, but is not limited to, CDU 201, optional RMU 202, andone or more server blades 203A-203E (collectively referred to as serverblades 203). Server blades 203 can be inserted into an array of serverslots respectively from frontend 204 or backend 205 of electronic rack200. Note that although there are five server blades 203A-203E shownhere, more or fewer server blades may be maintained within electronicrack 200. Also note that the particular positions of CDU 201, RMU 702,and server blades 203 are shown for the purpose of illustration only;other arrangements or configurations of CDU 201, RMU 202, and serverblades 203 may also be implemented. In one embodiment, electronic rack200 can be either open to the environment or partially contained by arack container, as long as the cooling fans can generate airflows fromthe frontend to the backend.

In addition, for at least some of the server blades 203, an optional fanmodule is associated with the server blade. In this embodiment, fanmodules 231A-231E, collectively referred to as fan modules 231, areassociated with server blades 203A-203E respectively. Each of the fanmodules 231 includes one or more cooling fans. Fan modules 231 may bemounted on the backends of server blades 203 or on the electronic rackto generate airflows flowing from frontend 204, traveling through theair space of the sever blades 203, and existing at backend 205 ofelectronic rack 200.

In one embodiment, CDU 701 mainly includes heat exchanger 711, liquidpump 712, and a pump controller (not shown), and some other componentssuch as a liquid reservoir, a power supply, monitoring sensors and soon. Heat exchanger 211 may be a liquid-to-liquid heat exchanger. Heatexchanger 211 includes a first loop with inlet and outlet ports having afirst pair of liquid connectors coupled to external liquid supply/returnlines 131-132 to form a primary loop. The connectors coupled to theexternal liquid supply/return lines 131-132 may be disposed or mountedon backend 205 of electronic rack 200. The liquid supply/return lines131-132, also referred to as room liquid supply/return lines, arecoupled to heat removal system 120 as described above. In addition, heatexchanger 211 further includes a second loop with two ports having asecond pair of liquid connectors coupled to liquid manifold 225 to forma secondary loop, which may include a supply manifold (also referred toas a rack liquid supply line) to supply cooling liquid to server blades203 and a return manifold (also referred to as a rack liquid returnline) to return warmer liquid back to CDU 201. Note that CDUs 201 can beany kind of CDUs commercially available or customized ones. Thus, thedetails of CDUs 201 will not be described herein.

Each of server blades 203 may include one or more IT components (e.g.,central processing units or CPUs, graphical processing units (GPUs),memory, and/or storage devices). Each IT component may perform dataprocessing tasks, where the IT component may include software installedin a storage device, loaded into the memory, and executed by one or moreprocessors to perform the data processing tasks. Server blades 203 mayinclude a host server (referred to as a host node) coupled to one ormore compute servers (also referred to as computing nodes, such as CPUserver and GPU server). The host server (having one or more CPUs)typically interfaces with clients over a network (e.g., Internet) toreceive a request for a particular service such as storage services(e.g., cloud-based storage services such as backup and/or restoration),executing an application to perform certain operations (e.g., imageprocessing, deep data learning algorithms or modeling, etc., as a partof a software-as-a-service or SaaS platform). In response to therequest, the host server distributes the tasks to one or more of theperformance computing nodes or compute servers (having one or more GPUs)managed by the host server. The performance compute servers perform theactual tasks, which may generate heat during the operations.

Electronic rack 200 further includes optional RMU 202 configured toprovide and manage power supplied to servers 203, fan modules 231, andCDU 201. RMU 202 may be coupled to a power supply unit (not shown) tomanage the power consumption of the power supply unit. The power supplyunit may include the necessary circuitry (e.g., an alternating current(AC) to direct current (DC) or DC to DC power converter, battery,transformer, or regulator, etc.,) to provide power to the rest of thecomponents of electronic rack 200.

In one embodiment, RMU 202 includes optimization module 221 and rackmanagement controller (RMC) 222. RMC 222 may include a monitor tomonitor operating status of various components within electronic rack200, such as, for example, computing nodes 203, CDU 201, and fan modules231. Specifically, the monitor receives operating data from varioussensors representing the operating environments of electronic rack 200.For example, the monitor may receive operating data representingtemperatures of the processors, cooling liquid, and airflows, which maybe captured and collected via various temperature sensors. The monitormay also receive data representing the fan power and pump powergenerated by the fan modules 231 and liquid pump 212, which may beproportional to their respective speeds. These operating data arereferred to as real-time operating data. Note that the monitor may beimplemented as a separate module within RMU 202.

Based on the operating data, optimization module 221 performs anoptimization using a predetermined optimization function or optimizationmodel to derive a set of optimal fan speeds for fan modules 231 and anoptimal pump speed for liquid pump 212, such that the total powerconsumption of liquid pump 212 and fan modules 231 reaches minimum,while the operating data associated with liquid pump 212 and coolingfans of fan modules 231 are within their respective designedspecifications. Once the optimal pump speed and optimal fan speeds havebeen determined, RMC 222 configures liquid pump 212 and cooling fans offan modules 231 based on the optimal pump speeds and fan speeds.

As an example, based on the optimal pump speed, RMC 222 communicateswith a pump controller of CDU 201 to control the speed of liquid pump212, which in turn controls a liquid flow rate of cooling liquidsupplied to the liquid manifold 225 to be distributed to at least someof server blades 203. Similarly, based on the optimal fan speeds, RMC222 communicates with each of the fan modules 231 to control the speedof each cooling fan of the fan modules 231, which in turn control theairflow rates of the fan modules 231. Note that each of fan modules 231may be individually controlled with its specific optimal fan speed, anddifferent fan modules and/or different cooling fans within the same fanmodule may have different optimal fan speeds.

FIG. 3 is a block diagram illustrating a processor cold plateconfiguration according to one embodiment. The processor/cold platestructure 400 can represent any of the processors/cold plate structuresof server blades 203 as shown in FIG. 2. Referring to FIG. 3, processor301 is plugged onto a processor socket mounted on printed circuit board(PCB) or motherboard 302 coupled to other electrical components orcircuits of a data processing system or server. Processor 301 alsoincludes a cold plate 303 attached to it, which is coupled to liquidsupply line 132 and liquid return line 131. A portion of the heatgenerated by processor 301 is removed by the cooling liquid via coldplate 303. The remaining portion of the heat enters into air space 305underneath, which may be removed by an airflow generated by cooling fan304.

FIG. 4 shows a top perspective view of a cold plate configurationaccording to one embodiment. Cold plate configuration 400 may representcold plate 303 and processor 301 of FIG. 3. Referring to FIG. 4, coldplate configuration 400 includes a cold plate assembly 401 and aprocessor assembly 402, where the cold plate assembly 401 can be mountedor attached to an exterior surface of the processor assembly 402 toreceive and remove the heat generated from a processor positioned in theprocessor assembly 402 using cooling liquid flowing within the coldplate assembly 401. Cold plate assembly 401 includes a cold plate 403disposed on a cold plate mounting bracket 404. Element 403 may bereferred to as a cold plate cover while element 404 may be referred toas a cold plate base, which when positioned together, encloses a coldplate therein. The cold plate design can be configured in a variety ofconfigurations or designs, which will not be described in detailsherein.

A heat sink is a passive heat exchange device that transfers the heatgenerated by an electronic or a mechanical device to a fluid medium,often air or a liquid coolant, where it is dissipated away from thedevice, thereby allowing regulation of the device's temperature atoptimal levels. In computers, heat sinks are used to cool centralprocessing units (CPUs) or graphics processors (GPUs). A heat sinktransfers thermal energy from a higher temperature device to a lowertemperature fluid medium. The fluid medium is frequently air, but canalso be water, refrigerants or oil. If the fluid medium is water orother type of heat transfer fluids, the heat sink is frequently called acold plate. Throughout this application, the terms of a cold plate and aheat sink are interchangeable terms for the purpose of illustration.

In one embodiment, cold plate 403 includes a liquid distribution channelor tube therein (not shown) to distribute cooling liquid to exchangeheat carried by cold plate 403, where the heat was exchanged fromprocessor 420 of processor assembly 402. The liquid distribution channelincludes an ingress port or inlet 405 to be coupled to a liquid supplyline (e.g., a rack liquid supply line) to receive the cooling liquidfrom a cooling liquid source. The liquid distribution channel furtherincludes an egress port or outlet 406 to be coupled to a liquid returnline (e.g., a rack liquid return line) to return the cooling liquidcarrying the exchanged heat back to the cooling liquid source.

In addition, according to one embodiment, cold plate mounting bracket404 includes a first set of mounting slots (also referred to as mountingholes) evenly disposed on the edges of cold plate mounting bracket 404.In this example, mounting slots 417-418 are disposed on one edge of coldplate mounting bracket 404, while there are other mounting slotsdisposed on the opposing edge of cold plate mounting bracket 404 such asmounting slots 415-416 as shown in FIG. 6. In one embodiment, samenumber of mounting slots is disposed on each side of the cold platemounting bracket 404. Although there are four mounting slots as shown inthis example, two for each edge, more or fewer mounting slots may alsobe implemented. In one embodiment, each of the mounting slots is in anasymmetric shape, such as, for example, an ellipse shape or rectangularshape.

The first set of mounting slots 415-418 are aligned with a second set ofmounting slots 421-424 when cold plate assembly 401 is mounted ontoprocessor assembly 402 by aligning guide pins 431A-431B with guide pinholes 432A-432B, for example, as shown in FIG. 5A in a top perspectiveview and FIG. 5B in a bottom perspective view. Once the first set ofmounting slots are aligned with the second set of mounting slots, amounting pin can be inserted through each of the aligned mounting slots.In this example, mounting pins 411-414 can be inserted through mountingslots 415-418 of cold plate mounting bracket 404 and mounting slots421-424 of processor mounting bracket 430 respectively.

According to one embodiment, each mounting pin is inserted through thecenter of a spring, such as spring 441, before entering thecorresponding mounting slot. A spring is an elastic object that storesmechanical energy. Springs are typically made of spring steel. When aconventional spring, without stiffness variability features, iscompressed or stretched from its resting position, it exerts an opposingforce approximately proportional to its change in length (thisapproximation breaks down for larger deflections). The rate or springconstant or spring coefficient of a spring is the change in the force itexerts, divided by the change in deflection of the spring, designed tooperate with a compression load, so the spring gets shorter as the loadis applied to it:

F=−kx

where x is the displacement vector—the distance and direction the springis deformed from its equilibrium length; f is the resulting forcevector—the magnitude and direction of the restoring force the springexerts; and k is the force coefficient or force constant of the spring,a constant that depends on the spring's material and construction.

Referring back to FIG. 4, the diameter of the spring coil of the springis larger than at least the smallest dimension of a mounting slot, suchthat the spring is prevented from entering the mounting slot. Thediameter of the spring coil is also smaller than a head of the mountingpin, such that the spring is prevented from being removed while themounting pin is inserting into the mounting slot. When the mounting pinenters a mounting slot, the spring is compressed to provide propermounting pressure on the cold plate mounting bracket 404 to push thecold plate towards the processor mounting bracket 430. The spring of themounting pin is compressed by the head of the mounting pin and the coldplate mounting bracket when the mounting pin enters the mounting slot.FIGS. 5A-5B and 6 show a top perspective view, a bottom perspectiveview, and a top view of a cold plate attached to a processor accordingto certain embodiments.

FIGS. 7A and 7B are block diagrams illustrating an example of a mountingpin configuration according to one embodiment. Referring to FIG. 7A, amounting pin includes a head portion 711, a shank portion 712, and a tipportion 713, as shown in a first side view 701, a second side view 702,and a cross view or bottom view 703. The cross section of head portion711 and shank portion 712 may be in a relatively circle shape. The sizeor diameter of head portion 711 is designed such that it is suitable forbeing grabbed or held on by fingers of an operator to push, pull, androtate the mounting pin. The size or diameter of shank portion 712 issmaller than the size of any of the mounting slots, while the size ordiameter of head portion 711 is larger than the size of any mountingslot. As a result, the shank portion 712 can go through a mounting slotwhile the head portion 711 is blocked as shown in FIG. 7B.

According to one embodiment, as shown in cross view 703, the crosssection of tip portion 713 is in an asymmetric shape. Particularly, theshape of the cross section of tip portion 713 is relatively conformingto the shape of a mounting slot. For example, if the shape of themounting slot is in an ellipse or rectangular shape, the shape of thecross section of the tip portion is significantly in an ellipse orrectangular shape respectively. As a result, a mounting pin can onlyinsert through a mounting slot in a particular angle or orientation thatis aligned with the angle or orientation associated with the mountingslot.

In one embodiment, a longer dimension 721 (e.g., along longitudinalaxis) of the cross section of tip portion 713 is larger than a shorterdimension of a mounting slot (e.g., dimension 602 of mounting slot 422of FIG. 6) and smaller than a longer dimension of the mounting slot(e.g., dimension 601 of mounting slot 422). A shorter dimension 722(e.g., along lateral axis) of the cross section of tip portion 713 issmaller than the shorter dimension of the mounting slot. As a result,the mounting pin can only insert through the mounting slot on a firstangle or orientation that is aligned with the shape of the mountingslot.

As described above, the diameter of the spring coil of spring 715 islarger than at least the shorter dimension of the mounting slot. As aresult, as shown in FIG. 7B, when the mounting pin is inserted throughthe mounting slot via a first angle, for example, by pressing a fingerof an operator and pushing downwardly, spring 715 is compressed betweenhead portion 711 and cold plate mounting bracket 404. Note that the tipportion 713 can only go through the mounting slot when its longitudinalaxis is aligned with the longitudinal axis of the mounting slot. Oncetip portion 713 goes through a mounting slot across both the cold platemounting bracket 404 and processor mounting bracket 430, the tip portion713 can be turned horizontally from the first angle to a second angle tointerlock the cold plate mounting bracket 404 and processor mountingbracket 430 together. In one embodiment, the difference between thefirst angle and the second angle is approximately 90 degrees. Forexample, an operator can simply use fingers holding the head portion 711to turn the mounting pin from the first angle to the second anglewithout requiring any tool. Alternatively, the operator can use a screwdriver to turn the mounting pin to different angles or orientations.

When the tip portion 713 is positioned along the second angle, themounting pin is referred to as in a locked position. When the mountingpin is in a locked position, the longitudinal axis of the cross sectionof the tip portion 713 is no longer aligned with the longitudinal axisof the mounting slot, as shown in FIG. 5B and FIG. 7B. Meanwhile, thespring 715 compressed by head portion 711 and the cold plate mountingbracket 404 due to the locked position of tip portion 713 continuesapplying pressure to push the cold plate mounting bracket 404 andprocessor mounting bracket 430 towards each other. As a result, the tipportion 713 is prevented from being retracted through the mounting slot,which keeps the cold plate mounting bracket 404 and processor mountingbracket 430 interlocked together.

According to one embodiment, spring 715 is designed with a forcecoefficient (also referred to as a force constant or spring constant)such that it provides a proper range of pressure that is greater than afirst predetermined threshold designed to provide sufficient pressure tocause the cold plate mounting bracket 404 in good contact with a surfaceof the processor for heat transfer. In addition, the pressure is lessthan a second predetermined threshold that corresponds to a maximumpressure the processor allows without causing damage to the processor.Similarly, when there is a need to disassemble the package, one cansimply turn the mounting pin from the second angle back to the firstangle, and mounting pin can be retracted and removed through themounting slot. Thereafter, the cold plate assembly can be separated fromthe processor assembly. Note that a single server blade can containmultiple cold plate assemblies attached with multiple processorassemblies, and some of them may be cascaded together by daisy chainingtheir respective liquid distribution channels, as shown in FIG. 8.

In the foregoing specification, embodiments of the invention have beendescribed with reference to specific exemplary embodiments thereof. Itwill be evident that various modifications may be made thereto withoutdeparting from the broader spirit and scope of the invention as setforth in the following claims. The specification and drawings are,accordingly, to be regarded in an illustrative sense rather than arestrictive sense.

1. A cooling module assembly for cooling a processor of a dataprocessing system in an electronic rack of a data center, the coolingmodule assembly comprising: a cold plate to be positioned adjacent to anexterior surface of a processor to receive heat radiated from theprocessor; a liquid distribution channel formed within the cold plate todistribute a cooling liquid through the cold plate to exchange the heatcarried by the cold plate, wherein the liquid distribution channelincludes an ingress port to be coupled a liquid supply line to receivethe cooling liquid from an external liquid source, wherein the ingressport is disposed on a first edge of the cold plate, and an egress portto be coupled to a liquid return line to return the cooling liquidhaving the exchanged heat back to the external liquid source, whereinthe egress port is disposed on a second edge of the cold plate oppositeto the first edge; and a cold plate mounting bracket attached to thecold plate to mount the cold plate onto the external surface of theprocessor, wherein the cold plate mounting bracket includes a first setof mounting slots to be aligned with a second set of mounting slotsdisposed on a processor mounting bracket that mounts the processor ontoa motherboard of the data processing system, wherein the first set ofmounting slots is disposed on a third edge of the cold plate mountingbracket and the second set of mounting slots is disposed on a fourthedge of the cold plate mounting bracket opposite to the third edge,wherein the third edge and the fourth edge are different edges than thefirst and second edges, wherein the third edge of the cold platemounting bracket further comprises a first set of one or more aligningguide pins disposed thereon and extended downwardly, and the fourth edgeof the cold plate mounting bracket further comprises a second set of oneor more aligning guide pins disposed thereon and extended downwardly,wherein when the cold plate mounting bracket together with the coldplate is mounted onto the processor mounting bracket, the aligning guidepins of the first set and second set are inserted into correspondingguide pin holes disposed on the processor mounting bracket, such thatthe mounting slots of the cold plate mounting bracket are aligned withthe mounting slots of the processor mounting bracket, wherein the firstset of mounting slots and the second set of mounting slots allow one ormore mounting pins to be inserted therethrough in a first angle and torotate from the first angle to a second angle after the insertion tointerlock the cold plate with the exterior surface of the processor;wherein each mounting pin is configured to insert through a center of aspring in order to insert through a corresponding mounting slot of thefirst set such that the spring is compressed when the mounting pin is ina locked position, thereby providing a force to push the cold platemounting bracket and the processor mounting bracket together so as toprovide adequate contact between the cold plate and the processor. 2.(canceled)
 3. (canceled)
 4. The cooling module assembly of claim 1,wherein a force coefficient of the spring is selected such that theforce applied to the processor is greater than a first predeterminedthreshold and less than a second predetermined threshold to allowtransferring the heat to the cold plate without applying too muchpressure to potentially damage the processor.
 5. The cooling moduleassembly of claim 4, wherein the force coefficient of the spring isconfigured based on a design specification of the processor, such thatthe force applied to the processor due to a compression of the springwhen the mounting pin is in the locked position is less than a maximumforce represented by the second predetermined threshold that can beapplied to the processor specified by the design specification.
 6. Thecooling module assembly of claim 1, wherein each mounting pin comprises:a head portion; a tip portion; and a shank portion coupling the headportion to the tip portion, wherein a cross section of the tip portionis configured to have a cross section shape conforming to an asymmetricshape of the mounting slots of the first set and the second set.
 7. Thecooling module assembly of claim 6, wherein a longitudinal dimension ofthe tip portion is larger than a lateral dimension of each mountingslot, and wherein a lateral dimension of the tip portion is smaller thanthe lateral dimension of the mounting slot.
 8. The cooling moduleassembly of claim 7, wherein each mounting pin is inserted throughcorresponding mounting slots of the first set and the second set in afirst angle, such that a longitudinal axis of the mounting pin isaligned with a longitudinal axis of the corresponding mounting slots,and wherein when mounting pin is rotated from the first angle to thesecond angle, the longitudinal axis of the mounting pin is not alignedwith the longitudinal axis of the corresponding mounting slots.
 9. Thecooling module assembly of claim 8, wherein each mounting pin in alocked position allows the tip portion and the head portion of themounting pin to lock the cold plate mounting bracket of a correspondingcold plate and the processor mounting bracket of the correspondingprocessor together.
 10. The cooling module assembly of claim 6, whereinat least the shank portion of each mounting pin is inserted through thespring, and wherein the spring is compressed between the head portionand the cold plate mounting bracket when the mounting pin is insertedthrough the mounting slots of the first set and second set.
 11. Thecooling module assembly of claim 10, wherein when the mounting pin is inthe locked position, the tip portion of the mounting pint prevents themounting pin from being retracted from the mounting slot of theprocessing mounting bracket, while the spring pulls the tip portionagainst the processor mounting bracket to interlock with each other. 12.The cooling module assembly of claim 6, wherein the asymmetric shape ofeach mounting slot is an ellipse shape or a rectangular shape.
 13. Anelectronic rack of a data center, comprising: a rack liquid supply line;a rack liquid return line; and a stack of server blades coupled to therack cooling liquid supply line and the rack cooling liquid return line,each server blade representing a data processing system, wherein eachserver blade includes one or more processors each attached to a coolingmodule assembly, wherein each cooling module assembly includes a coldplate to be positioned adjacent to an exterior surface of a processor toreceive heat radiated from the processor, a liquid distribution channelformed within the cold plate to distribute a cooling liquid through thecold plate to exchange the heat carried by the cold plate, wherein theliquid distribution channel includes an ingress port to be coupled therack liquid supply line to receive the cooling liquid from an externalliquid source, wherein the ingress port is disposed on a first edge ofthe cold plate, and an egress port to be coupled to the rack liquidreturn line to return the cooling liquid having the exchanged heat backto the external liquid source, wherein the egress port is disposed on asecond edge of the cold plate opposite to the first edge, and a coldplate mounting bracket attached to the cold plate to mount the coldplate onto the external surface of the processor, wherein the cold platemounting bracket includes a first set of mounting slots to be alignedwith a second set of mounting slots disposed on a processor mountingbracket that mounts the processor onto a motherboard of the dataprocessing system, wherein the first set of mounting slots is disposedon a third edge of the cold plate mounting bracket and the second set ofmounting slots is disposed on a fourth edge of the cold plate mountingbracket opposite to the third edge, wherein the third edge and thefourth edge are different edges than the first and second edges, whereinthe third edge of the cold plate mounting bracket further comprises afirst set of one or more aligning guide pins disposed thereon andextended downwardly, and the fourth edge of the cold plate mountingbracket further comprises a second set of one or more aligning guidepins disposed thereon and extended downwardly, wherein when the coldplate mounting bracket together with the cold plate is mounted onto theprocessor mounting bracket, the aligning guide pins of the first set andsecond set are inserted into corresponding guide pin holes disposed onthe processor mounting bracket, such that the mounting; slots of thecold plate mounting bracket are aligned with the mounting slots of theprocessor mounting bracket, wherein the first set of mounting slots andthe second set of mounting slots allow one or more mounting pins to beinserted therethrough in a first angle and to rotate from the firstangle to a second angle after the insertion to interlock the cold platewith the exterior surface of the processor; wherein each mounting pin isconfigured to insert through a center of a spring in order to insertthrough a corresponding mounting slot of the first set such that thespring is compressed when the mounting pin is in a locked position,thereby providing a force to push the cold plate mounting bracket andthe processor mounting bracket together so as to provide adequatecontact between the cold plate and the processor.
 14. (canceled) 15.(canceled)
 16. The electronic rack of claim 13, wherein a forcecoefficient of the spring is selected such that the force applied to theprocessor is greater than a first predetermined threshold and less thana second predetermined threshold to allow transferring the heat to thecold plate without applying too much pressure to potentially damage theprocessor.
 17. A data center, comprising: a room liquid supply linecoupled to a cooling liquid source; a room liquid return line coupled tothe cooling liquid source; and an array of electronic racks, each of theelectronic racks including a rack liquid supply line coupled to the roomliquid supply line; a rack liquid return line coupled to the room liquidreturn line; and a stack of server blades coupled to the rack coolingliquid supply line and the rack cooling liquid return line, each serverblade representing a data processing system, wherein each server bladeincludes one or more processors each attached to a cooling moduleassembly, wherein each cooling module assembly comprises a cold plate tobe positioned adjacent to an exterior surface of a processor to receiveheat radiated from the processor, a liquid distribution channel formedwithin the cold plate to distribute a cooling liquid through the coldplate to exchange the heat carried by the cold plate, wherein the liquiddistribution channel includes an ingress port to be coupled the rackliquid supply line to receive the cooling liquid from the room liquidsupply line, wherein the ingress port is disposed on a first edge of thecold plate, and an egress port to be coupled to the rack liquid returnline to return the cooling liquid having the exchanged heat back to theroom liquid return line, wherein the egress port is disposed on a secondedge of the cold plate opposite to the first edge, and a cold platemounting bracket attached to the cold plate to mount the cold plate ontothe external surface of the processor, wherein the mounting bracketincludes a first set of mounting slots to be assigned with a second setof mounting slots disposed on a processor mounting bracket that mountsthe processor onto a motherboard of the data processing system, whereinthe first set of mounting slots is disposed on a third edge of the coldplate mounting bracket and the second set of mounting slots is disposedon a fourth edge of the cold plate mounting bracket opposite to thethird edge, wherein the third edge and the fourth edge are differentedges than the first and second edges, wherein the third edge of thecold plate mounting bracket further comprises a first set of one or morealigning guide pins disposed thereon and extended downwardly, and thefourth edge of the cold plate mounting bracket further comprises asecond set of one or more aligning guide pins disposed thereon andextended downwardly, wherein when the cold plate mounting brackettogether with the cold plate is mounted onto the processor mountingbracket, the aligning guide pins of the first set and second set areinserted into corresponding guide pin holes disposed on the processormounting bracket, such that the mounting slots of the cold platemounting bracket are aligned with the mounting slots of the processormounting bracket. wherein the first set of mounting slots and the secondset of mounting slots allow one or more mounting pins to be insertedthrough via a first angle and to rotate from the first angle to a secondangle, after the insertion to interlock the cold plate with the exteriorsurface of the processor; wherein each mounting pin is configured toinsert through a center of a spring in order to insert through acorresponding mounting slot of the first set such that the spring iscompressed when the mounting pin is in a locked position, therebyproviding a force to push the cold plate mounting bracket and theprocessor mounting bracket together so as to provide adequate contactbetween the cold plate and the processor.
 18. (canceled)
 19. (canceled)20. The data center of claim 17, wherein a force coefficient of thespring is selected such that the force applied to the processor isgreater than a first predetermined threshold and less than a secondpredetermined threshold to allow transferring the heat to the cold platewithout applying too much pressure to potentially damage the processor.21. The electronic rack of claim 16, wherein the force coefficient ofthe spring is configured based on a design specification of theprocessor, such that the force applied to the processor due to acompression of the spring when the mounting pin is in the lockedposition is less than a maximum force represented by the secondpredetermined threshold that can be applied to the processor specifiedby the design specification.
 22. The electronic rack of claim 13,wherein each mounting pin comprises: a head portion; a tip portion; anda shank portion coupling the head portion to the tip portion, wherein across section of the tip portion is configured to have a cross sectionshape conforming to an asymmetric shape of the mounting slots of thefirst set and the second set.
 23. The electronic rack of claim 22,wherein a longitudinal dimension of the tip portion is larger than alateral dimension of each mounting slot, and wherein a lateral dimensionof the tip portion is smaller than the lateral dimension of the mountingslot.
 24. The data center of claim 20, wherein the force coefficient ofthe spring is configured based on a design specification of theprocessor, such that the force applied to the processor due to acompression of the spring when the mounting pin is in the lockedposition is less than a maximum force represented by the secondpredetermined threshold that can be applied to the processor specifiedby the design specification.
 25. The data center of claim 17, whereineach mounting pin comprises: a head portion; a tip portion; and a shankportion coupling the head portion to the tip portion, wherein a crosssection of the tip portion is configured to have a cross section shapeconforming to an asymmetric shape of the mounting slots of the first setand the second set.
 26. The data center of claim 25, wherein alongitudinal dimension of the tip portion is larger than a lateraldimension of each mounting slot, and wherein a lateral dimension of thetip portion is smaller than the lateral dimension of the mounting slot.